Search PubMed⌕ Search

Biomedical subjects

D Bohn

Publications and source records attributed to D Bohn.

At least 55 records · Page 3Linked to original sources
PubMed1995

Renal replacement therapy after repair of congenital heart disease in children. A comparison of hemofiltration and peritoneal dialysis.

The development of renal failure necessitating peritoneal dialysis after cardiac operations is associated with a reported mortality greater than 50%. Improved fluid removal and nutritional support have been reported with the use of continuous arteriovenous hemofiltration and continuous venovenous hemofiltration techniques. We have compared our experience with all three techniques in managing children who required renal replacement therapy after cardiac operations in terms of efficacy (fluid removal, calorie intake, and clearance of urea and creatinine), complications, and outcome. Over a 5-year period renal replacement therapy was initiated in 42 children, and in 34 of them it was successfully established for more than a 24-hour period: 17 were managed with peritoneal dialysis, 8 with continuous arteriovenous hemofiltration, and 9 with continuous venovenous hemofiltration. A net negative fluid balance was achieved in only 6 (35%) patients treated with peritoneal dialysis compared with 50% of those treated with continuous venovenous hemofiltration and 89% of those treated with continuous venovenous hemofiltration. In terms of nutritional support, calorie intake increased by 43% after peritoneal dialysis was started compared with 515% and 409% in the arteriovenous and venovenous hemofiltration groups, respectively, (p < 0.005). The serum urea levels fell by 36% (p = 0.02) and 39% (p = 0.005) compared with pre-therapy levels with arteriovenous and venovenous hemofiltration, respectively, and the creatinine content was reduced by 19% and 33% (p = 0.003). Neither parameter was reduced in the peritoneal dialysis group. We conclude that the use of hemofiltration as a renal replacement therapy after surgical correction of congenital heart disease offers significant advantages over the more traditional approach of peritoneal dialysis. In addition, we suggest that a more aggressive approach to the management of fluid overload and nutritional depletion with hemofiltration may result in a decrease in the very high mortality seen in renal failure after cardiac operations.

Acute Kidney Injury↗
PubMed1995

A canine study of cold water drowning in fresh versus salt water.

OBJECTIVE: To compare the pathophysiologic changes occurring during drowning in cold fresh water and cold salt water with reference to viability. DESIGN: Randomized, prospective, controlled submersion experiments in two contrasting cold liquids. SETTING: A laboratory at a large university-affiliated medical institution. SUBJECTS: Thirteen healthy, anesthetized mongrel dogs. Three dogs served as controls and were immersed but not submerged. The remainder were submerged in cold fresh water or cold salt water (4 degrees C). INTERVENTIONS: Catheters were placed in the femoral artery, right carotid artery and right internal jugular vein. Electrocardiogram, pneumogram, and rectal temperatures were measured continuously during submersion/immersion. MEASUREMENTS AND MAIN RESULTS: Cold water submersion with drowning produced a large initial decrease in carotid artery temperature (approximately 7.5 degrees C in the first 2 mins) compared with a minor decrease (approximately 0.8 degrees C with immersion). No significant differences were noted in the rate of decrease of temperature between drowning in fresh water and salt water. During cold fresh water drowning, aspiration produced gross hemodilution with an average increase in body weight of 16.5%. Hematocrit values, serum sodium concentrations, and osmolality decreased while serum potassium concentrations, catecholamines, and free hemoglobin increased. All measured biochemical data (except PaO2) remained at viable levels. By contrast, during cold salt water drowning, average body weight increased by only 6%, with hemoconcentration and a shrinkage of vascular volume. Hematocrit and hemoglobin values increased by 30%, but initial plasma free hemoglobin values remained unchanged. Serum sodium concentrations, osmolality, and potassium concentrations increased rapidly to critical levels. CONCLUSIONS: On submersion in cold water, all of the experimental animals developed tachypnea immediately, followed by aspiration with predictable effects. The biochemical and pathophysiologic changes in cold water drowning approximated those changes reported for warm water drowning for both fresh and salt water with one exception and continued aspiration of cold water produced extremely rapid core cooling as long as the circulation remained intact. This process of acute submersion hypothermia may protect the brain temporarily from lethal damage, as reported in cases of cold fresh water drowning. Concentrations of circulating catecholamines increased exponentially in both groups of test animals. Clinically, their acute effects on the circulation, compounded by significant hypothermia and extreme anoxia, must hamper the detection of residual circulation at rescue and may play a role in sudden death from cold water in the absence of drowning.

Animals↗
PubMed1995

Determinants of success in pediatric cardiac patients undergoing extracorporeal membrane oxygenation.

BACKGROUND: The purpose of this retrospective study is to determine the possible predictors of successful cardiac recovery using extracorporeal membrane oxygenation (ECMO) and the practical limits of ECMO support. METHODS: Information was gathered on 31 consecutive children with myocardial failure who could not be resuscitated with other means and underwent ECMO at the Hospital for Sick Children before January 1994. RESULTS: Of the children who underwent ECMO as a means of cardiac rescue, 14/31 (45%) were weaned successfully. Two distinct groups of children were evident based on their initial indications for ECMO: those who had postcardiotomy myocardial dysfunction (n = 25) and those with cardiomyopathy or myocarditis (n = 6). Children with residual defects after cardiotomy (n = 10) did not survive ECMO. Four of the 6 children with cardiomyopathy or myocarditis were weaned successfully. In either group of patients ECMO support beyond 6 days failed to resuscitate the myocardium; all attempts to violate this "time barrier" in our study inevitably failed. CONCLUSIONS: Postcardiotomy residual defects are a contraindication to ECMO. If children with residual defects are excluded, successful weaning from ECMO can be achieved in almost 70%, with almost all recovery occurring with the first 6 days of ECMO.

Cardiac Catheterization↗
PubMed1994

Effects of extracorporeal membrane oxygenation on morphine pharmacokinetics in infants.

OBJECTIVES: To study the effect of extracorporeal membrane oxygenation (ECMO) on the pharmacokinetics of morphine in infants. DESIGN: A prospective, comparative study of morphine pharmacokinetics during and after ECMO. SETTING: The pediatric intensive care unit at a children's hospital. PATIENTS: Seven infants, aged 1 day to 12 months, requiring ECMO. INTERVENTION: Infusion of morphine. MEASUREMENT AND MAIN RESULTS: Steady-state concentrations of morphine were used to generate a morphine clearance rate. Plasma clearance rate of morphine increased from 0.574 +/- 0.3 L/kg/hr to 1.058 +/- 0.727 L/kg/hr after discontinuation of ECMO (p < .01). Two infants experienced a clinical picture consistent with opioid withdrawal. CONCLUSION: Infants requiring morphine after ECMO may require higher dose rates to maintain adequate sedation.

Extracorporeal Membrane Oxygenation↗
PubMed1994

A simple method for monitoring the concentration of inhaled nitric oxide.

Nitric oxide is a potent endogenous vasodilator involved in the homeostatic control of systemic blood pressure. It has also recently been demonstrated that when inhaled in low concentrations it acts as a specific pulmonary vasodilator. The concept of inhaled nitric oxide as a form of therapy is almost an anathema to anaesthetists. However, nitric oxide is being used increasingly for the treatment of persistent pulmonary hypertension of the neonate and in the adult respiratory distress syndrome. One major limitation to its frequent and widespread use is the problem of measuring the concentration of nitric oxide delivered. Currently, the gold standard technique used is chemiluminesence. However, the equipment required is costly and can be difficult to use. If the use of inhaled nitric oxide increases and it develops a therapeutic role then its applications may be limited only to centres which can afford such equipment. Others may be prevented from using a potentially valuable therapy due to lack of a controlled delivery system for nitric oxide. An inexpensive, simple alternative technique to chemiluminesence is described, which will allow most intensive care units the freedom to use inhaled nitric oxide if necessary.

Administration, Inhalation↗
PubMed1993

Morphine pharmacokinetics in children following cardiac surgery: effects of disease and inotropic support.

The pharmacokinetics of morphine have not been previously studied in children following cardiac surgery for tetralogy of Fallot (TOF) or transposition of the great arteries (TGA). Morphine steady-state pharmacokinetics were studied in 21 children undergoing repair of TOF, TGA, or atrio-ventricular septal defects (AVSD). Children with TOF or TGA had increased right-sided pressures with no differences between the groups. Children with TOF had significantly faster clearance rates of morphine (1.39 +/- 0.37 L/kg/h) than children following the Fontan procedure (0.86 +/- 0.31 L/kg/h, P < 0.01). When stratifying children by their postsurgical needs for inotropic support, those needing epinephrine, dopamine, or dobutamine at more than 10 micrograms/kg/min had significantly slower clearance rates (0.73 +/- 0.3 L/kg/h) when compared to the rest of the patients (1.5 +/- 0.41 L/kg/h, P < 0.05). Because most children needing inotropic support underwent the Fontan procedure, it is conceivable that their cardiovascular status had a major impact on morphine metabolism. These results suggest a 50% reduction in morphine dosage in children requiring inotropic support following cardiac surgery.

Blood Pressure↗
PubMed1993

Severe hypernatremic dehydration and hyperkalemia in an infant with gastroenteritis secondary to rotavirus.

A case of severe hypernatremic dehydration (sodium, 191 mmol/L) with associated severe hyperkalemia (potassium, 11.2 mmol/L) and hyperosmolality (502 mOsm/kg) is described in a 3-month-old infant secondary to acute infection with rotavirus. The patient was managed with i.v. fluid resuscitation in conjunction with intracranial pressure monitoring and was discharged well and without any permanent sequelae. Review of the literature reveals the case described to be the most profound example of hypernatremic dehydration with a favorable outcome reported from diarrheal illness. Strategies for management of hypernatremic dehydration are discussed.

Dehydration↗
PubMed1993

Preliminary studies of the effects of extracorporeal membrane oxygenator on the disposition of common pediatric drugs.

There is an increased use of extracorporeal membrane oxygenation (ECMO) in the last 15 years for critically ill neonates. While receiving ECMO therapy, the critically ill infant needs various medications. We performed an in vitro study to evaluate the potential effect of the membrane oxygenator on drug extraction. Two closed ECMO circuits were set up at rates of 320 ml/min. One circuit was new and the other was used clinically for 5 days. Morphine at 8 ng/ml, gentamicin 10 micrograms/ml, vancomycin 40 micrograms/ml, phenobarbital 20 micrograms/ml, and phenytoin 20 micrograms/ml were injected into the circuit at 1-h intervals. Blood samples were drawn from the circuit at 10, 30, 60, and 240 minutes after injection. In the new circuit, drugs were eliminated as follows: vancomycin 36%, gentamicin 10%, phenobarbital 17%, phenytoin 43%, morphine 36%. In the used system, levels fell to a much smaller extent: vancomycin 11%, phenobarbital 6%, gentamicin 0%, phenytoin 0%, and morphine 16%. In a child receiving 20 micrograms/kg/h infusion of morphine, steady-state concentrations of 68.2 ng/ml fell to 11.6 ng/ml after changing the membrane. Our data indicate that the ECMO is associated with lowering of the concentrations of commonly used medications and that this process may depend partially on how new the membrane is. Before these changes may lead to new dosing guidelines for small children receiving ECMO, more experiments with new and used systems are warranted, as well as with different types of ECMO.

Anti-Bacterial Agents↗
PubMed1993

Hyperplasia of pulmonary arterial media in infantile familial pulmonary hypertension associated with severe metabolic acidosis.

Two female siblings, offspring of consanguinous parents, died at 10 and 12 wk of age following short illnesses characterized clinically by hypoxia and severe metabolic acidosis. Cardiac catheterization confirmed severe pulmonary hypertension in the second infant, who survived 6 wk after onset of symptoms and 4 wk after admission to hospital; extensive investigations failed to identify any inborn metabolic error. At autopsy, small pulmonary arteries/arterioles in both cases showed marked medial thickening due to smooth muscle hyperplasia; concentric intimal fibrosis was present focally in the older infant. Compared morphometrically with small pulmonary arteries in 20 infantile controls who died of Reye's syndrome (n = 8), a Reye's-like illness (n = 5) or an identified metabolic error associated with metabolic acidosis (n = 7), intraacinar pulmonary arteries in both cases, were significantly more numerous and had a significantly greater relative medial thickness. We suggest that an autosomal recessive gene caused or potentiated the pulmonary medial hyperplasia. The latter finding, compared with medial hypertrophy, is rarely described as the morphologic basis of pulmonary hypertension, and its occurrence may be restricted to early infancy. In this family, the relationship between hypertensive pulmonary arteriopathy and severe metabolic acidosis remains speculative.

Acidosis↗
PubMed1991

Respiratory failure due to retained esophagus: a complication of esophageal replacement.

Recurrent fistulas occur in about 10% of infants treated for esophageal atresia with distal tracheoesophageal fistula. Failed repair of a recurrent fistula rarely requires esophageal replacement and removal or diversion of the native esophagus. We present a patient who underwent multiple operations for recurrent tracheosophageal fistula whose native esophagus was eventually replaced with a colonic interposition graft. Over the subsequent 9 years he experienced failure to thrive, respiratory distress, and repeated pulmonary infections attributed to chronic aspiration. Eventually, he developed respiratory failure and required endotracheal intubation and mechanical ventilation. He became increasingly difficult to ventilate and, in spite of aggressive efforts, suffered a cardiac arrest from which he could not be resuscitated. At postmortem, a dilated blind segment of native esophagus, which was compressing and obstructing the malacic trachea, was found in the posterior mediastinum. Death was caused by massive air embolus, which was in turn attributed to the high airway pressures needed to ventilate the patient. Tracheal compression by a remnant of native esophagus should be considered in the differential diagnosis of respiratory failure after esophageal replacement.

Child↗
PubMed1991

Use of the Pediatric Risk of Mortality score to predict nosocomial infection in a pediatric intensive care unit.

OBJECTIVE: To define infection rates in patients with Pediatric Risk of Mortality (PRISM) scores greater than and less than 10 on admission to the pediatric ICU (PICU). DESIGN: Descriptive. SETTING: An 18-bed PICU admitting patients of all ages except nonsurgical neonates; within a 585-bed tertiary care pediatric hospital. PATIENTS: Patients admitted to the PICU from July 1987 to February 1988 inclusive. Of 685 admitted, 480 were followed for greater than or equal to 72 hr. METHODS: The baseline state of the patients on admission was determined by a designated intensivist using the PRISM score. Other variables included age, length of stay, and hospital day of onset of infection. Infections were identified by a designated intensivist who undertook prospective daily bedside observation, chart, radiographic, and laboratory review. MEASUREMENTS AND MAIN RESULTS: Equal portions of patients had PRISM scores less than and greater than 10. Significantly more infections occurred in the high PRISM population (10.8% vs. 3.4%, p less than .001). This association held through age, service, and length of stay. Sensitivity, specificity, positive and negative predictive values of a PRISM score greater than 10 were 75%, 53%, 11%, and 97%, respectively. Bacteremias accounted for 36% of infections, skin/eye/drain site 22%, respiratory 16%, wound 15%, and urine 9%. The most prevalent organisms were coagulase-negative staphylococci (32%), Pseudomonas aeruginosa (23%), Candida sp. (20%), and S. aureus (9%). CONCLUSIONS: A PRISM score greater than 10 on PICU admission characterizes a population within the PICU at increased risk of infection. However, 93% of patients did not develop infection and thus, a negative predictive value of 97% yields little additional information.

Adolescent↗
PubMed1991

Lymphocytic pneumonitis following bone marrow transplantation in severe combined immunodeficiency.

Lung disease in patients with severe combined immune deficiency (SCID) undergoing bone marrow transplantation (BMT) is most commonly caused by infection. Noninfectious episodes of pulmonary disease following BMT are more frequently encountered in patients with hematologic disorders or malignancy and are probably related to ablation therapy or graft-versus-host disease (GVHD). In contrast, patients with SCID do not receive chemotherapy before an HLA-identical allogeneic BMT and they do not suffer significant GVHD. We report a patient who developed severe lung disease during the period of rapid engraftment following an HLA-identical allogeneic bone marrow transplantation. Lung biopsy showed dense lymphocytic infiltrates in the alveolar septae and no evidence of infection. Following the idea that the acute recruitment of engrafted lymphocytes may have contributed to or caused the pulmonary disease, we have attempted to suppress cellular immunity by administering high-dose methylprednisolone. The patient's lung disease rapidly improved and eventually completely resolved.

Bone Marrow↗
PubMed1990

Cervical spine injuries in children.

Cardiorespiratory arrest occurring immediately after multiple injuries is usually assumed to be due to severe cerebral injury, acute hemorrhage, or airway obstruction. We have identified a group of 19 children (mean age, 6.3 years) who presented with absent vital signs (VSA) or severe hypotension, unexplained by blood loss, where these findings were caused by injury to the high cervical spine and cord, demonstrated either by X-ray or postmortem examination. Fourteen had radiologic evidence of injury to the spine between C1 and C3. In two patients the bony injury was at the C6-7 level, while in two patients the cervical spine X-ray was normal. Eighteen of the 19 children were initially resuscitated but died from a combination of hypoxic/ischemic encephalopathy and cerebral injury. Sixteen patients underwent postmortem examination and in 13 there was evidence of cord laceration, up to and including cord transection. These findings demonstrate a distinct pattern of "juvenile" cervical spine injury involving the high spine and cord which results in either apnea and cardiorespiratory arrest, or severe hypotension. This previously unrecognized cause of cardiorespiratory arrest should be considered in all children presenting with VSA after multiple trauma, even when there is no apparent radiologic abnormality of the cervical spine.

Adolescent↗
PubMed1990

Thoracic vascular injuries: a post mortem study.

We reviewed the coroner's records for all pediatric (less than 16 years of age) trauma fatalities in Ontario (population, 9.5 million) for the period January 1, 1985, through December 31, 1987. Twenty-six (8%) of the 322 cases for which complete autopsy data were available had major thoracic vascular injuries. Twenty-five deaths occurred within 6 hours of injury. The majority of patients had at least one AIS 6 injury. The aorta was the most frequently injured vessel. Major thoracic vascular injuries are more common among children than previous reports suggest, probably because they are rapidly fatal. Many deaths occur in the field, at local hospitals, or in transit before the patient can reach a trauma center. Efforts to reduce the number of total thoracic vascular injuries should focus on primary and secondary prevention.

Adolescent↗